The use of acoustic signal based systems, such as sonar and echo sounding systems, for detecting and/or tracking a contact or target is well known in the art. Sonar systems, including active sonar systems, have been used to detect and track contacts or targets, e.g., submarines, in a water medium such as the ocean. Echo sounding systems have been used to map the ocean floor.
Sonar systems generally provide information about a contact's distance, bearing, and identification. However, certain physical characteristics of the medium surrounding a contact such as temperature, temperature gradients, salinity (in the case of ocean water), and other factors affect the accuracy and quality of the contact information. To compensate for these effects, active sonar systems and echo sounding systems have, at times, used single or multiple acoustic signal beams in conjunction with an array of acoustic signal or pulse (ping) energy sources, e.g., projectors, and an array of acoustic signal detectors, e.g., hydrophones.
To further compensate for the effects of ocean water characteristics, sonar systems have employed acoustic signal or echo processing methods after detection using computer algorithms to compensate for acoustic signal ambiguities based, for example, on noise cancellation, weighted averaging, phase offset corrections, and acoustic signal parameter simulations. Other methods have also been employed such as single-ping matched filter/beam former detection, empirical clustering and classification of contacts, Kalman filtering, and MAP tracking algorithms. These methods, however, do not adequately address contact imaging and tracking in a highly cluttered environment.
Another drawback of the prior art is that acoustic signal detection techniques have an embedded loss of information in that signal changes between pings are not measured in a detailed manner. This results in inadequate detection and tracking of target in highly cluttered environments, especially occluded and crossing targets.
As a result, a need exists for systems and methods that enable the imaging and tracking of contacts within a medium using post detection signal processing with image processing methods to improve the accuracy and quality of contact imaging and tracking.